Image Reading Device

ABSTRACT

An image reading device comprising: a document placing portion; a conveyor; a reading unit configured to read an image of the document, wherein the reading unit includes: an image sensor; a support which supports the image sensor, wherein in the case of reading the image of the document conveyed by the conveyor, the support is to be stopped at a predetermined reading position; a guide; and a driving unit, wherein the reading unit further includes: a release unit configured to release the contact with the guide by separating the support from the guide when the support is moved toward the predetermined reading position; and a contact portion configured to contact with the support separated from the guide by the release unit when the support is moved toward the predetermined reading position.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No.2012-190059 filed on Aug. 30, 2012, the entire subject matter of whichis incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to an image reading device.

BACKGROUND

There is an image reading device called a flatbed type. In general, suchan image reading device includes an image sensor having reading elementsarranged in a main scanning direction and a carriage moving the imagesensor in a sub-scanning direction. The carriage has a structure capableof moving along a guide shaft. As such a guide shaft, a round bar shapedmetal shaft is used (e.g., see JP-A-H11-266347).

SUMMARY

Meanwhile, in the above-described flatbed type image reading device, oneimage reading device is additionally provided with an automatic documentfeeder (hereinafter referred to as an “ADF”). In the case of using theADF, the above-described carriage and image sensor are stopped at apredetermined reading position. If a document is conveyed by the ADF,the document passes through a point which faces the image sensor at thereading position during conveyance, and at that time, the image sensorreads an image of the document.

In such an image reading device, many parts may not be interposedbetween the image sensor and the guide shaft. Accordingly, even inconsideration of tolerance of their part dimensions or tolerance of thepositioning precision between the parts, the image sensor and the guideshaft are in a state where their positions can be determined withrelatively good precision, and the reading quality of the image isstabilized in the reading using the flatbed.

However, between the image sensor and the ADF, the parts interposedbetween the image sensor and the guide shaft are increased and manyparts are additionally interposed between the guide shaft and the ADF.Accordingly, in consideration of the tolerance of their part dimensionsor the tolerance of the positioning precision between the parts withrespect to all the parts, it is correspondingly difficult to positionthe image sensor and the ADF with good precision.

If the positioning precision of the image sensor and the ADF is low, thearrangement direction of the reading elements of the image sensor (mainscanning direction) and the conveyance direction of the document by theADF (sub-scanning direction) may be slightly inclined and may not be atright angles. Since the degrees of inclination are different from eachdevice, the inclination becomes the cause where unevenness occurs in thereading quality of the image using the ADF.

Accordingly, this disclosure provides at least an image reading device,which is configured to determine relative positional relations betweenan image sensor and an ADF with better precision than that in therelated art.

Hereinafter, the configuration adopted in this disclosure will bedescribed. An image reading device of this disclosure includes: adocument placing portion on which a document is placed; a conveyorconfigured to convey a document along a predetermined conveyance path;and a reading unit configured to read an image of the document. Thereading unit includes: an image sensor having a plurality of readingelements arranged in a main scanning direction; a support which supportsthe image sensor and is movable together with the image sensor in asub-scanning direction that is orthogonal to the main scanningdirection; a guide, which guides the support in the sub-scanningdirection through coming in contact with the support when the support ismoved in the sub-scanning direction; and a driving unit configured tomove the support in the sub-scanning direction. In the case of readingthe image of the document placed on the document placing portion, thesupport is moved in the sub-scanning direction within a predeterminedreading range, and in the case of reading the image of the documentconveyed by the conveyor, the support is to be stopped at apredetermined reading position. In the case of moving in thesub-scanning direction within the predetermined reading range, thesupport is moved while keeping in contact with the guide. The readingunit further includes: a release unit configured to release the contactwith the guide by separating the support and the guide when the supportis moved toward the predetermined reading position; and a contactportion configured to contact with the support separated from the guideby the release unit when the support is moved toward the predeterminedreading position.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and additional features and characteristics of thisdisclosure will become more apparent from the following detaileddescriptions considered with the reference to the accompanying drawings,wherein:

FIG. 1 is a perspective view illustrating an external appearance of thewhole multifunction peripheral;

FIG. 2 is a block diagram illustrating the internal configuration of themultifunction peripheral;

FIG. 3 is a perspective view illustrating an external appearance of ascanner unit and an ADF unit;

FIG. 4 is a perspective view illustrating a structure in the vicinity ofa hinge portion;

FIG. 5 is a plan view illustrating a scanner unit;

FIG. 6 is a longitudinal cross-sectional view illustrating a schematicstructure of a scanner unit and an ADF unit;

FIG. 7 is a perspective view illustrating a guide unit and a releaseunit.

FIG. 8A is a longitudinal cross-sectional view illustrating a statewhere a slider portion and a guide unit are at a contact position asseen from the front side of the device, and FIG. 8B is a longitudinalcross-sectional view illustrating a range taken along line A-A in FIG.8A.

FIG. 9A is a longitudinal cross-sectional view illustrating a statewhere a slider portion and a guide unit are at separate positions asseen from the front side of the device, and FIG. 9B is a longitudinalcross-sectional view illustrating a range taken along line B-B in FIG.9A.

FIGS. 10A and 10B are explanatory views illustrating the state ofpositioning of a support and a contact portion.

DETAILED DESCRIPTION

Hereinafter, embodiments of this disclosure will be described. In thisembodiment, an exemplified image reading device is configured as amultifunction peripheral having other functions (e.g., print function,copy function, facsimile transmission/reception function, and the like)in addition to the function (scan function) as the image reading device.In the following description, for simple explanation of relativepositional relations between respective portions of the multifunctionperipheral, respective directions, that is, upper, lower, left, right,front, and rear directions, as described in the drawings will be used.

[Structure of a Multifunction Peripheral]

As illustrated in FIG. 1, a multifunction peripheral 1 includes a mainbody unit 2, a scanner unit 3 mounted on an upper side of the main bodyunit 2, and an ADF unit 4 mounted on an upper side of the scanner unit3. On an upper portion of the front side of the main body unit 2, anoperation panel 6 that is operated by a user is provided. On a lowerportion of the main body unit 2, a feeder cassettes 8A and 8B, in whichrecorded medium before printing is accommodated, are mounted.

In the main body unit 2, as illustrated in FIG. 2, a controller 11, animage forming unit 12, a LAN communication unit 13, and a PSTNcommunication unit 14 are provided in addition to the operation panel 6.

The controller 11 includes a known CPU 11A, a ROM 11B, a RAM 11C, anNVRAM 11D, and an interface unit 11E. The CPU 11A executes apredetermined process according to a control program stored in the ROM11B or the RAM 11C, and thus the control of respective units of themultifunction peripheral 1 is executed.

The image forming unit 12 is provided with an electrographic or ink jetprint mechanism. The LAN communication unit 13 includes a communicationinterface device supporting wireless LAN, and a communication interfacedevice supporting wire LAN. The PSTN communication unit 14 includesvarious kinds of devices that are necessary to connect to the publicswitched telephone network (PSTN).

In the operation panel 6, input devices (e.g., a touch panel, variouskinds of buttons, and switches), which is operated when a user providesvarious kinds of commands to the multifunction peripheral, and an outputdevice (e.g., liquid crystal display device) for notifying a user of theoperating state of the multifunction peripheral 1.

The scanner unit 3 includes a line type image sensor 21 having aplurality of reading elements, and a support 23 supporting the imagesensor 21. Further, the scanner unit 3 includes a motor 25, a gearmechanism 27 that is driven by the motor 25, and a timing belt 29 thatis driven by the gear mechanism 27, and the above-described support 23is connected to the timing belt 29. The motor 25 receives a drivingsignal from a motor driving unit 11F provided in an interface unit 11Eof the controller 11 to operate. The power that is generated by themotor 25 is transmitted to the support 23 through the gear mechanism 27and the timing belt 29, and as a result, the support 23 is moved in theleft/right direction together with the image sensor 21.

The ADF unit 4 includes conveyance rollers 31 to 39 conveying thedocument along a predetermined conveyance path. Further, in the ADF unit4, a motor 41 and a gear mechanism 43 that is driven by the motor 41 areprovided. The motor 41 receives a driving signal from a motor drivingunit 11G provided in the interface unit 11E of the controller 11 tooperate. The power that is generated by the motor 41 is transmitted tothe conveyance rollers 31 to 39 through the gear mechanism 43. On theother hand, some of the conveyance rollers 31 to 39 is driving rollersdirectly driven by the gear mechanism 43, and other rollers are drivenrollers rotated to follow the driving rollers or the document.

[Attachment Structure of the ADF Unit for the Scanner Unit]

As illustrated in FIG. 1, on an upper portion of the scanner unit 3, acover member 51 is provided, and a platen glass 53 is attached to thecover member 51. The cover member 51 includes a frame portion 51Asurrounding four sides of the platen glass 53, and a partition portion51B dividing an upper surface of the platen glass 53 into a first area53A and a second area 53B. In this embodiment, one sheet of platen glass53 is divided into the first area 53A and the second area 53B. However,the first area 53A and the second area 53B may be provided by differentplaten glasses 53.

As illustrated in FIG. 3, the ADF unit 4 is attached to the scanner unit3 to be opened and closed by a pair of hinge portions 55 provided atpositions that are spaced apart from each other in the left/rightdirection. On an upper end side of the hinge portion, as illustrated inFIG. 4, a bearing portion 55A is provided, and a rotating shaft 4A isprovided on the side of the ADF unit 4. The rotating shaft 4A isrotatably supported by the bearing portion 55A.

If the ADF unit 4 is opened, as illustrated in FIG. 1, the upper surfaceof the platen glass 53 is exposed to an outside. On the other hand, ifthe ADF unit 4 is closed, the ADF unit 4 functions as a cover thatcovers the upper surface of the platen glass 53.

As illustrated in FIGS. 3 and 4, the hinge portion 55 is fixed to thescanner unit 3 by a screw 57. In the cover member 51 provided in thescanner unit 3, as illustrated in FIG. 3, two positioning projections 59are provided to be corresponded to one hinge portion 55.

In the case of fixing the hinge portion 55 to the scanner unit 3, thepositioning projection 59 is inserted into a positioning hole 55B formedon the side of the hinge portion 55, so that the hinge portion 55 isfixed to the scanner unit 3 in a state where it is positioned withrelatively good precision with respect to the cover member 51. In thisembodiment, the hinge portions 55 are provided at two points on the rearend side of the device main body. However, the number of hinge portions55 is not limited to 2, and the attachment method is not limited to theabove-described fixing method in so far as the hinge portion 55 is fixedto the scanner unit 3.

[Details of the Scanner Unit]

In the scanner unit 3, as illustrated in FIGS. 3 and 5, theabove-described image sensor 21, the support 23, and the timing belt 29are provided. On the other hand, FIG. 5 illustrates both a state, wherethe image sensor 21 has moved to a position P1 together with the support23, and a state, where the image sensor 21 has moved to a position P2.

In this embodiment, the image sensor 21 is composed of a CIS (ContactImage Sensor). A plurality of reading elements provided in the imagesensor 21 are arranged in the front/rear direction in the multifunctionperipheral 1. Hereinafter, the front/rear direction that is thearrangement direction of the reading elements is called a main scanningdirection.

As illustrated in FIG. 5, the support 23 has a carriage unit 23A, and aslider portion 23B that is attached to a bottom portion of the carriageunit 23A. The slider portion 23B is provided in the vicinity of thecenter in the main scanning direction of the carriage unit 23A, and itis made of a material having higher slidability than that of thecarriage unit 23A. Specifically, in this embodiment, the carriage unit23A is formed of ABS resin, and the slider portion 23B is formed ofpolyacetal resin (POM).

On an upper surface side of a base portion 3A that is provided in thescanner unit 3, a guide unit 61 that extends in the left/right directionis provided. The base portion 3A and the guide unit 61 are integrallyformed of a resin material. If the timing belt is driven, the support 23slides on the guide unit 61. Hereinafter, the left/right direction thatis the moving direction of the image sensor 21 and the support is calleda sub-scanning direction.

In the vicinity of both ends in the front/rear direction of the imagesensor 21, as illustrated in FIGS. 5 and 6, a spacer 63 that isinterposed between the image sensor 21 and the platen glass 53 isattached. Further, a compression spring 65 is interposed between thesupport 23 and the image sensor 21.

The image sensor 21 and the spacer 63 are always in a compressed statetoward the side of the platen glass 53. Accordingly, when the support 23is moved, even if the support 23 slightly moves upward and downward, thespacer 63 keeps the contact state with the lower surface of the platenglass 53, and the image sensor 21 is maintained in parallel to the lowersurface of the platen glass 53.

On the lower surface of the partition portion 51B that the cover member51 has, a reference member 67 is incorporated. The reference member 67is a member formed to have white portions and black portions for apredetermined pattern. When reading the image, in order to performoriginal point position correction and shading correction of the imagesensor 21, the reference member 67 is read by the image sensor 21.

[Details of the ADF Unit]

In the ADF unit 4, as illustrated in FIG. 6, the plurality of conveyancerollers 31 to 39 as described above are provided. If the conveyancerollers 31 to 39 are driven, the document can be conveyed along apredetermined conveyance path (a path indicated by a dashed line).

In the case where the multifunction peripheral 1 is used as an ADF typeimage scanner, the image sensor 21 in the scanner unit 3 moves to theposition P1 as shown in FIG. 5, and then it is stopped (hereinafter, theposition P1 is also called a reading position P1). Further, theconveyance rollers 31 to 39 in the ADF unit 4 convey the document alongthe above-described conveyance path.

The conveyed document passes through a position where the document comesin contact with the second area 53B of the platen glass 53 in theleft/right direction in the middle of the conveyance path. At thisposition, a document pressing portion 71 is provided. When the conveyeddocument passes through the position where the document pressing portion71 is positioned, the document pressing portion 71 presses the documenttoward the second area 53B, and the document comes in close contact withthe second area 53B of the platen glass 53. The image sensor 21 that isat the reading position P1 faces the second area 53B and the documentpressing portion 71. In this state, the image sensor 21 can read theimage of the document that passes through the reading position P1 by thereading elements arranged in the main scanning direction.

As illustrated in FIG. 6, on the lower surface of the ADF unit 4, anelastic member 73 is provided at a position that comes in contact withthe first area 53A of the platen glass 53 when the ADF unit 4 is closed.The elastic member 73 is a laminated body including a foaming resinlayer as its upper layer and a resin film layer as its lower layer.

In the case where the multifunction peripheral 1 is used as an imagescanner, a document is placed on the first area 53A of the platen glass53. If needed, the ADF unit 4 is closed. At this time, the elasticmember 73 presses the document placed on the first area 53A from theupper side, and the document comes in close contact with the first area53A of the platen glass 53. In this state, the image sensor 21 moves inthe sub-scanning direction together with the support 23.

In this embodiment, during the forward movement to the left, the imagesensor 21 is within a predetermined reading range A1, and the image ofthe document placed on the first area 53A of the platen glass 53 is readby the reading elements that are arranged in the main scanningdirection. Thereafter, if the image reading is terminated, the imagesensor 21 returns to the initial position through the return movement inthe left direction.

[Positioning Mechanism of the Support at the Reading Position P1]

In the vicinity of the left end side of the guide unit 61, asillustrated in FIG. 7, a first projection portion 81 and a secondprojection portion 82 are formed. The first projection portion 81 andthe second projection portion 82 are formed at positions that areseparated from each other in the left/right direction, and are at thepositions where they are seen to overlap each other as seen from thesub-scanning direction.

Further, both the first projection portion 81 and the second projectionportion 82 project upward from the upper end of the guide unit 61, butthe upper end of the second projection portion is at a higher position(upper side) than the upper end of the first projection portion 81. Onthe right end side of the first projection portion 81, an inclinationportion 81A having an upward slop from the right side to the left sideis formed. Even on the right end side of the second projection portion82, an inclination portion 81A having an upward slop from the right sideto the left side is formed. The upper ends of the first projectionportion 81 and the second projection portion that continue on the upperend sides of the inclination portions 81A and 82A are flat planes.

On the other hand, on the slider portion 23B, as illustrated in FIGS.8A, 8B, 9A, and 9B, a first convex portion 83 and a second convexportion that project downward are formed. The first convex portion 83 isformed at a position where the support 23 comes in contact with thefirst projection portion 81 when the support 23 is moved to the readingposition P1, and the second convex portion 84 is formed at a positionwhere the support 23 comes in contact with the second projection portion82 when the support 23 is moved to the reading position P1 (see FIG.8A).

When the slider portion 23B moves to the position where the sliderportion 23B is separated from the first projection portion 81 and thesecond projection portion 82, the slider portion 23B moves in theleft/right direction while keeping a state where the upper surfaceportion of the slider portion 23B is at a drop position H1. At thistime, a groove portion that is formed on the lower side of the sliderportion 23B comes in contact with the guide unit 61 at both sides of theguide unit 61 in the front/rear direction in the vicinity of the upperend of the guide unit 61. (See FIG. 8B).

In such a contact state, the slider portion 23B is unable to bedisplaced in the rotating direction along the surface perpendicular tothe upper/lower direction (i.e. surface parallel to the front/reardirection or the left/right direction). Accordingly, the support 23 ispositioned at a position where the length direction of the support 23and the length direction of the guide unit 61 are orthogonal to eachother on the basis of the guide unit 61.

On the other hand, if the support 23 is moved in the left direction andis reached the reading position P1, as illustrated in FIGS. 9A and 9B,the slider portion 23B runs onto the first projection portion 81 and thesecond projection portion 82. At this time, since the inclinationportions 81A and 82A are provided on the first projection portion 81 andthe second projection portion 82, respectively, the slider portion 23Bcan be smoothly guided to the upper side of the first projection portion81 and the second projection portion 82 as the support 23 move in theleft direction.

Further, the upper ends of the first projection portion 81 and thesecond projection portion 82 have different positions (heights), andthus the positions (heights) of the upper ends of the first projectionportion 81 and the second projection portion 82 are changed. Throughthis, when the support 23 reaches the reading position P1, the lower endof the second convex portion 84 passes in the left direction along theupper side of the first projection portion 81 and runs onto the secondprojection portion 82 without coming in contact with the upper end ofthe first projection portion 81.

If the slider portion 23B runs onto the first projection portion 81 andthe second projection portion 82, the support 23 is moved slightlyupward without changing the inclination for the left/right direction andthe front/rear direction, and the upper surface portion of the sliderportion 23B is displaced to a rise position H2. Further, since the upperends of the first projection portion 81 and the second projectionportion 82 are flat surface and come in surface contact with the firstprojection portion 83 and the second projection portion 84, it becomespossible to support the rising slider portion 23B in a stable state withrespect to the guide unit 61.

Further, in this state, the groove portion 85 that is formed on thelower side of the slider portion 23B is separated from the upper end ofthe guide 61 (see FIG. 9B). In this state, the slider portion 23B issupported by the upper ends of the first projection portion 81 and thesecond projection portion 82 and the timing belt 29, and it is in acondition to be able to be displaced in the rotating direction along thesurface perpendicular to the upper/lower direction (i.e. surface inparallel to the front/rear direction and the left/right direction). Thatis, the first projection portion 81 and the second projection portion 82function as release units to release the contact with the guide unit 61when the support 23 is moved toward the reading position P1.

Further, as illustrated in FIGS. 5 and 9A, a pair of contacted portions87 are formed at positions separated from each other in the front/reardirection. When the support 23 is moved toward the reading position P1,the contact portion 51 c that is integrally formed on the cover member51 comes in contact with the contacted portion 87 (see FIG. 9A).

Accordingly, as illustrated in FIG. 10A, if the contact portion 51Ccomes in contact with one of the contacted portions 87, even though thesupport 23 is slightly inclined against the contact portion 51, thesupport 23 is rotated in the direction in which the other of thecontacted portions 87 approaches the contact portion 51C as illustratedin FIG. 10B. As a result, the support 23 is positioned on the basis ofthe cover member 51.

The support 23 is positioned on the basis of the cover member 51 at thereading position P1, and it is positioned on the basis of the guide unit61 when it moves in the reading range A1. As described above, the ADFunit 4 is supported by the hinge portion 55, and the cover member 51 ofthe hinge portion 55 is positioned with good precision. However, anothercomponent is interposed between the hinge portion 55 and the guide unit61, and thus the hinge portion 55 and the guide unit 61 are not indirect positioning relations.

Accordingly, the tolerance of the relative position for the ADF unit 4becomes smaller than that of the guide unit 61. Accordingly, if thesupport 23 is moved toward the reading position P1, the positioning onthe basis of the guide member 61 is released, and it is changed to thepositioning based on the cover member 51. Accordingly, the positioningaccuracy between the support 23 and the ADF unit 4 can be furtherimproved.

[Effects]

As described above, according to the above-described multifunctionperipheral 1, in the case of reading the image of the document conveyedin the ADF unit 4, the support 23 comes in contact with the contactportion 51C, and thus is positioned at a portion where the tolerance ofthe relative position for the ADF unit 4 is smaller than that for theguide unit 61.

Accordingly, as compared with the case where the support 23 ispositioned against the guide unit 61, the tolerance accumulated betweenthe support 23 and the ADF unit 4 can be reduced, and thus the qualitydeterioration of the read image can be suppressed due to the toleranceaccumulated between the support 23 and the ADF unit 4.

According to the above-described multifunction peripheral 1, since therelease unit is constructed by the first projection portion 81 and thesecond projection portion 82 formed to project from the guide unit 61,the release unit has a simple structure, and thus can be easily preparedas compared with a case where the release unit having a complicatedstructure is prepared.

According to the above-described multifunction peripheral 1, when thesupport 23 is moved toward the reading position P1, the support 23 runsonto the first projection portion 81 and the second projection portion82 at the same time, and then it is separated from the guide unit 61while performing parallel movement. Accordingly, when the support 23runs onto the projection portions, the inclination of the support 23 ischanged, and thus the behavior of the support 23 becomes stabilized.Further, even after the support 23 runs onto the first projectionportion 81 and the second projection portion 82, the support 23 can besupported on the first projection portion 81 and the second projectionportion 82 in more stable state.

According to the above-described multifunction peripheral 1, since thefirst projection portion 81 and the second projection portion 82 are inpositions where they are seen to overlap each other as seen from thesub-scanning direction, a region required for arrangement of theprojection portions becomes compact as compared with a case where theplurality of projection portions are in the position to not overlap eachother as seen from the sub-scanning direction. Further, According to theabove-described multifunction peripheral 1, in the moving directionwhere the support 23 is moved toward the reading position P1, theprojection height of the first projection portion 81 positioned in themore upstream side is set low, and the projection height of the secondprojection portion 82 positioned in the downstream side is set high. Inother words, the highest portion of the first projection portion 81positioned in the upstream side is lower than the highest portion of thesecond projection portion 82 positioned in the downstream side.Accordingly, although the first projection portion 81 and the secondprojection portion 82 are in positions where they are seen to overlapeach other as seen from the sub-scanning direction, the second convexportion 84 can pass through the first projection portion 81 withoutrunning onto the first projection portion 81 in the upstream side whenthe support 23 is moved to the reading position P1. Accordingly, unlikea case where the projection height of the first projection portion 81 inthe upstream side is higher than that of the second projection portion82 in the downstream side or a case where the projection heights of thefirst projection portion 81 and the second projection portion 82 areequal to each other, the support 23 can appropriately run onto thesecond projection portion 82 in the downstream side.

According to the above-described multifunction peripheral 1, since thefirst convex portion 83 and the second convex portion 84 are provided onthe side of the support 23, the frictional force that acts between thesupport 23 and the guide unit 61 is reduced as compared with a casewhere the support 23 comes in contact with the first projection portion81 and the second projection portion 82 at a surface that is larger thanthe front end of the first convex portion 83 and the second convexportion 84, and thus the state where the support 23 is positioned at theposition based on the guide unit 61 can be released more smoothly.

According to the above-described multifunction peripheral 1, when thesupport 23 runs onto the first projection portion 81 and the secondprojection portion 82, the support 23 comes in contact with theinclination portions 81A and 82A and then runs onto the first projectionportion 81 and the second projection portion 82 along the inclinationportions 81A and 82A. Accordingly, the support 23 can smoothly run ontothe first projection portion 81 and the second projection portion 82 ascompared with a case where the inclination portions 81A and 82A are notprovided.

According to the above-described multifunction peripheral 1, thereference member 67 can be appropriately read at a position that is notaffected by the first projection portion 81 and the second projectionportion 82.

Further, According to the above-described multifunction peripheral 1,the tolerance that can be accumulated between the ADF unit 4 and thecontact portion 51C becomes the tolerance between the cover member 51and the hinge portion 55 and the tolerance between the hinge portion 55and the ADF unit 4. Accordingly, the tolerance accumulated between theADF unit 4 and the support 23 can be reduced in the case where thesupport 23 is positioned on the basis of the contact portion 51C that isintegrally formed with the cover member 51, rather than in the casewhere the support 23 is positioned on the basis of the guide unit 61separated from the cover member 51, and thus the reading precision ofthe document can be heightened.

According to the above-described multifunction peripheral 1, since theguide unit 61 is made of a resin material, unlike the metal guide unit,the projection portions can be easily provided by a technique ofintegrally forming the guide unit 61 and the projection portions (e.g.,first projection portion 81 and the second projection portion 82).

According to the above-described multifunction peripheral 1, thematerial that forms the slider portion 23B has higher slidability thanthe material that forms the carriage unit 23A, and thus the respectiveperformances of the carriage unit 23A and the slider portion 23B can beoptimized as compared with a case where the whole support 23 isintegrally formed with the same material.

Other Embodiments

Although the embodiment of this disclosure have been described, thisdisclosure is not limited to the above-described detailed embodiments,and may be embodied in various forms.

For example, in the above-described embodiment, the first projectionportion 81 and the second projection portion 82 are exemplified as aspecific example of the release unit. However, the number of projectionportions are optional, and one projection portion or three or moreprojection portions may be configured. However, if one projectionportion is provided, the inclination is easy to occur on the supportwhen the support runs onto the projection portion, and thus it ispreferable that a plurality of projection portions are provided as inthe above-described embodiment so that the support runs onto theplurality of projections at the same time.

Further, if it is configured that the contact portion 51C of the covermember 51 and the support 23 are directly positioned, as theabove-described embodiment, such a configuration is not limited to theconfiguration that the projection-shaped contacted portions 87 areprovided in the support 23, but may have other shapes.

In the above-described embodiment, it is exemplified that the guide unit61 is formed of a resin material. However, the configuration of thisdisclosure can also be adopted even in the case where the metal guideshaft is adopted as the guide unit.

Further, in the above-described embodiment, the image reading deviceaccording to this disclosure is configured as the multifunctionperipheral. However, this is optional, and the configuration of thisdisclosure may be adopted in an image reading device, a copy machine, ora facsimile, which has a single function.

What is claimed is:
 1. An image reading device comprising: a documentplacing portion on which a document is placed; a conveyor configured toconvey a document along a predetermined conveyance path; and a readingunit configured to read an image of the document, wherein the readingunit comprises: an image sensor having a plurality of reading elementsarranged in a main scanning direction; a support which supports theimage sensor and is movable together with the image sensor in asub-scanning direction that is orthogonal to the main scanningdirection; a guide which guides the support in the sub-scanningdirection through coming in contact with the support when the support ismoved in the sub-scanning direction; and a driving unit configured tomove the support in the sub-scanning direction, wherein in the case ofreading the image of the document placed on the document placingportion, the support is moved in the sub-scanning direction within apredetermined reading range, and in the case of reading the image of thedocument conveyed by the conveyor, the support is to be stopped at apredetermined reading position, and wherein in the case of moving in thesub-scanning direction within the predetermined reading range, thesupport is moved while keeping in contact with the guide, wherein thereading unit further comprises: a release unit configured to release thecontact with the guide by separating the support and the guide when thesupport is moved toward the predetermined reading position; and acontact portion configured to contact with the support separated fromthe guide unit by the release unit when the support is moved toward thepredetermined reading position.
 2. The image reading device according toclaim 1, wherein the release unit comprises at least one projectionportion formed to project from the guide, and wherein the support isseparated from the guide by running onto the projection portion when thesupport is moved toward the predetermined reading position.
 3. The imagereading device according to claim 2, wherein a plurality of projectionportions are provided to be formed at positions that are separated fromeach other in the sub-scanning direction, and wherein the support isseparated from the guide by running onto the plurality of projectionportions at the same time when the support is moved toward thepredetermined reading position.
 4. The image reading device according toclaim 3, wherein the plurality of projection portions are arranged atpositions where the plurality of projection portions are seen to overlapeach other as seen from the sub-scanning direction, and wherein in amoving direction where the support is moved toward the predeterminedreading position, a projection height of the projection portions is setlow as the projection portions are positioned on an upstream side, whilethe projection height of the projection portions is set high as theprojection portions are positioned on a downstream side.
 5. The imagereading device according to claim 2, wherein the support has a convexportion that projects toward the projection portion at a position wherethe support comes in contact with the projection portion when thesupport is moved toward the predetermined reading position.
 6. The imagereading device according to claim 2, wherein in the moving directionwhere the support is moved toward the predetermined reading position,the projection portion is shaped so that a shape of a portion becomingthe upstream side has an inclination portion that has an upward slopfrom the upstream side to the downstream side, and wherein when thesupport is moved toward the predetermined reading position, the supportcomes in contact with the inclination portion and then runs onto theprojection portion along the inclination portion.
 7. The image readingdevice according to claim 1, wherein a reference member, which is readby the image sensor when a reference of the image read by the imagesensor is adjusted, is arranged between the predetermined reading rangeand the predetermined reading position, and wherein the projectionportion is provided in the downstream side than the reference member inthe moving direction where the support is moved toward the predeterminedreading position.
 8. The image reading device according to claim 1,wherein a cover that is a separate member from the guide is provided onan upper side of the guide, an upper portion of a main body of thedevice being configured by the cover, and the conveyor is mounted on thecover through a hinge portion, and wherein the contact portion isintegrally formed with the cover.
 9. The image reading device accordingto claim 1, wherein the guide is a resin component that is made by aresin material.
 10. The image reading device according to claim 1,wherein the support comprises a slider portion, which slides along theguide while coming in contact with the guide with a carriage on whichthe image sensor is attached.
 11. The image reading device according toclaim 11, wherein the slider portion is formed of a material havinghigher slidability than the carriage.
 12. The image reading deviceaccording to claim 1, wherein in the contact portion, tolerance of arelative position with respect to the conveyor is smaller than toleranceof a relative position with respect to the guide.